Windows XP - Internet Browsing EXTREMELY Slow (Painful)

Good morning,

Yes, it's true . . . I still have a Windows XP desktop that I dearly LOVE! It is running Windows XP Pro SP3. Installed ZoneAlarm Free Firewall Version 14.3.119.000 which runs along with Avast Free Anti-Virus Version 17.5.2302.

Regular applications (outside of Internet) are not too bad, but OMG! No matter what browser I use, my Internet browsing is rendered almost useless (including my Yahoo email). I have done much troubleshooting, have made various changes to both ZoneAlarm and Avast configurations with no luck. If I disable ZoneAlarm Free Firewall, everything speeds up back to normal. BUT, I need a firewall!

So, any help, suggestions, recommendations would be HUGELY appreciated. This has been enormously frustrating and I know there MUST be a way to fix this . . . . RIGHT?? :-) Thanks, in advance, to any help anyone can give.